Increased frequency of TIGIT+ CD4 T Cell subset in autoantibody-positive first-degree relatives of patients with rheumatoid arthritis

SLAM receptors regulate immune checkpoints via SAP and EAT- 2 in rheumatoid arthritis: association with disease activity

OBJECTIVE

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and immune dysregulation. This study aimed to investigate the role of SLAM family receptors (SLAMF1 and SLAMF7), immune checkpoint molecules (PD- 1 and TIGIT), and SH2-containing adaptor proteins (SAP and EAT- 2) in rheumatoid arthritis (RA) and their association with disease activity.

METHODS

A total of 50 RA patients (30 inactive, 20 active) and 20 healthy controls were enrolled. Real-time ​polymerase chain reaction (PCR) was used to assess the expression of target genes in peripheral blood mononuclear cells (PBMCs). Gene expression profiling datasets (GSE77298, GSE206848, GSE236924, GSE15573) were analyzed to identify differentially expressed genes (DEGs). Correlation of gene expression with Disease Activity Score 28-joint count (DAS28) was evaluated.

RESULTS

SLAMF1, SLAMF7, SAP, and EAT- 2 expression levels were significantly elevated in RA patients compared to controls. SLAMF1 and SAP expression correlated positively with DAS28 (r = 0.319, p = 0.02; r = 0.460, p = 0.0008, respectively). PD- 1 expression was higher in RA patients but showed no correlation with DAS28, while TIGIT expression was not significantly different. Bioinformatics analysis revealed significant upregulation of SLAMF7 and TIGIT in synovial tissues from RA patients.

CONCLUSION

SLAMF1 and SLAMF7 appear to contribute to RA pathogenesis by modulating immune cell activity and cytokine production. Elevated PD- 1 levels suggest a role in immune dysregulation. The interplay between SLAM receptors, immune checkpoints, and adaptor proteins may exacerbate T cell overactivity and chronic inflammation, offering potential therapeutic targets. Key Points •RA patients showed significantly higher expression of SLAMF1, SLAMF7, PD- 1, SAP, and EAT- 2 compared to healthy controls. •SLAMF1 and SAP expression correlated with disease activity, with SLAMF1 levels higher in active RA cases. •PD- 1 overexpression suggested immune dysregulation, while TIGIT showed no significant difference in RA patients. •The interplay between SLAM receptors, immune checkpoints, and adaptor proteins may contribute to RA pathogenesis and serve as potential therapeutic targets.

Exploring the Common Pathogenic Mechanisms of Psoriasis and Atopic Dermatitis: The Interaction between SGK1 and TIGIT Signaling Pathways

This study aims to explore the common pathogenic mechanisms of psoriasis and atopic dermatitis, two T-cell-mediated autoimmune diseases. Utilizing single-cell transcriptomic sequencing data, we revealed that Treg cells primarily express TIGIT in both psoriasis and atopic dermatitis, and identified a subset of macrophages that highly express SGK1. These cells can interact with T cells via the NECTIN2-TIGIT signaling pathway, inhibiting the differentiation of T cells into a pro-inflammatory phenotype, thereby uncovering a common immunoregulatory mechanism in both diseases. Furthermore, we discovered that inhibition of SGK1 exacerbates the inflammatory response in disease models of both conditions. These findings not only provide a new perspective for a common therapeutic strategy for psoriasis and atopic dermatitis but also highlight the importance of considering these molecular interactions in future treatments. Validation of these observations through further qPCR, immunofluorescence, and animal studies has identified potential new targets for the treatment of psoriasis and atopic dermatitis.

Comprehensive Co-Inhibitory Receptor (Co-IR) Expression on T Cells and Soluble Proteins in Rheumatoid Arthritis

Co-inhibitory receptors (Co-IRs) are essential in controlling the progression of immunopathology in rheumatoid arthritis (RA) by limiting T cell activation. The objective of this investigation was to determine the phenotypic expression of Co-IR T cells and to assess the levels of serum soluble PD-1, PDL-2, and TIM3 in Taiwanese RA patients.

METHODS

Co-IRs T cells were immunophenotyped employing multicolor flow cytometry, and ELISA was utilized for measuring soluble PD-1, PDL-2, and TIM3. Correlations have been detected across the percentage of T cells expressing Co-IRs (MFI) and different indicators in the blood, including ESR, high-sensitivity CRP (hsCRP), 28 joint disease activity scores (DAS28), and soluble PD-1/PDL-2/TIM3.

RESULTS

In RA patients, we recognized elevated levels of PD-1 (CD279), CTLA-4, and TIGIT in CD4+ T cells; TIGIT, HLA-DR, TIM3, and LAG3 in CD8+ T cells; and CD8+CD279+TIM3+, CD8+HLA-DR+CD38+ T cells. The following tests were revealed to be correlated with hsCRP: CD4/CD279 MFI, CD4/CD279%, CD4/TIM3%, CD8/TIM3%, CD8/TIM3 MFI, CD8/LAG3%, and CD8+HLA-DR+CD38+%. CD8/LAG3 and CD8/TIM3 MFIs are linked to ESR. DAS28-ESR and DAS28-CRP exhibited relationships with CD4/CD127 MFI, CD8/CD279%, and CD8/CD127 MFI, respectively. CD4+CD279+TIM3+% was correlated with DAS28-ESR (p = 0.0084, N = 46), DAS28-CRP (p = 0.007, N = 47), and hsCRP (p = 0.002, N = 56), respectively. In the serum of patients with RA, levels of soluble PD-1, PDL-2, and Tim3 were extremely elevated. CD4+ TIM3+% (p = 0.0089, N = 46) and CD8+ TIM3+% (p = 0.0305, N = 46) were correlated with sTIM3 levels; sPD1 levels were correlated with CD4+CD279+% (p < 0.0001, N = 31) and CD3+CD279+% (p = 0.0084, N = 30).

CONCLUSIONS

Co-IR expressions on CD4+ and CD8+ T cells, as well as soluble PD-1, PDL-2, and TIM3 levels, could function as indicators of disease activity and potentially play crucial roles in the pathogenesis of RA.

TIGIT: An emerging immune checkpoint target for immunotherapy in autoimmune disease and cancer

Immune checkpoints (ICs), also referred to as co-inhibitory receptors (IRs), are essential for regulating immune cell function to maintain tolerance and prevent autoimmunity. IRs, such as programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), have been shown to possess immunoregulatory properties that are relevant to various autoimmune diseases and cancers. Tumors are characterized by suppressive microenvironments with elevated levels of IRs on tumor-infiltrating lymphocytes (TILs). Therefore, IR blockade has shown great potential in cancer therapy and has even been approved for clinical use. However, other IRs, including cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT), may also represent promising targets for anti-tumor therapy. The increasing importance of IRs in autoimmune diseases has become apparent. In mouse models, TIGIT pathway blockade or TIGIT deficiency has been linked to T cell overactivation and proliferation, exacerbation of inflammation, and increased susceptibility to autoimmune disorders. On the other hand, TIGIT activation has been shown to alleviate autoimmune disorders in murine models. Given these findings, we examine the effects of TIGIT and its potential as a therapeutic target for both autoimmune diseases and cancers. It is clear that TIGIT represents an emerging and exciting target for immunotherapy in these contexts.

Chemokines and chemokine receptors as promising targets in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that commonly causes inflammation and bone destruction in multiple joints. Inflammatory cytokines, such as IL-6 and TNF-α, play important roles in RA development and pathogenesis. Biological therapies targeting these cytokines have revolutionized RA therapy. However, approximately 50% of the patients are non-responders to these therapies. Therefore, there is an ongoing need to identify new therapeutic targets and therapies for patients with RA. In this review, we focus on the pathogenic roles of chemokines and their G-protein-coupled receptors (GPCRs) in RA. Inflamed tissues in RA, such as the synovium, highly express various chemokines to promote leukocyte migration, tightly controlled by chemokine ligand-receptor interactions. Because the inhibition of these signaling pathways results in inflammatory response regulation, chemokines and their receptors could be promising targets for RA therapy. The blockade of various chemokines and/or their receptors has yielded prospective results in preclinical trials using animal models of inflammatory arthritis. However, some of these strategies have failed in clinical trials. Nonetheless, some blockades showed promising results in early-phase clinical trials, suggesting that chemokine ligand-receptor interactions remain a promising therapeutic target for RA and other autoimmune diseases.